An autopsy has confirmed that James Gandolfini, acclaimed star of "The Sopranos," died of a heart attack.

"Today we received the results of the autopsy, which stated he died of a heart attack, of natural causes," family spokesperson Michael Kobold told reporters Friday in Rome, adding that "nothing else was found in his system."

On Thursday, Dr. Claudio Modini, head of the emergency department at the Policlinico Umberto I Hospital in Rome, attributed the actor's death to cardiac arrest, although the exact cause for it was not immediately known.

In his statement, Kobold also briefly elaborated on Gandolfini's final hours, during which he visited the Vatican and dined with his family at the Boscolo Exedra Hotel while awaiting the arrival of his sister.

"He had a wonderful day," Kobold said. "We are all devastated by this loss. James was a devoted husband, a loving father of two children, a brother and cousin you could always count on. We thank you for the privacy you have afforded us during this difficult time."

James Gandolfini, who played Tony Soprano on HBO's "The Sopranos," has died of a possible heart attack, HBO has confirmed. Here's a look back at his career. RELATED PHOTOS: Life in pictures | Celebrities react on Twitter

Critic's notebook: As Tony Soprano in HBO's mob drama, the actor found his greatest role. It's too bad the movies didn't know how to make the most of his prodigious talents as a leading man the way 'The Sopranos' did.

James Gandolfini, the most important actor in the most influential television series of the last decade and a half, died suddenly Wednesday, in Italy. He was only 51, and though he had been a busy working actor -- in film and onstage as well as on TV -- for two decades, and had (with writer...